The present invention relates to apparatus for severing webs or strips, especially webs or strips which consist of flexible material, and more particularly to improvements in apparatus which can be used with advantage for subdivision of webs of exposed and developed photographic material into discrete prints or groups of prints. Still more particularly, the invention relates to improvements in apparatus for severing and stacking prints or analogous sections of flexible web-like material.
Webs of exposed and developed photographic prints are customarily severed in an apparatus wherein the web is transported stepwise to place successive frame lines between neighboring prints into register with the mobile knife of a severing device. The web is held at a standstill while the mobile knife performs a working stroke to separate the foremost print from the next-following print or prints. The freshly separated prints are caused or allowed to descend into a collecting receptacle. As a rule, a first group of advancing rolls draws the web off a reel on which the web is stored in convoluted form, and a second group of advancing rolls is located immediately downstream of the severing station. The rolls of the second group are set in motion when the mobile knife of the severing device completes a working stroke to thereby advance the freshly severed print into register with the collecting receptacle. Thus, the rolls of the second group engage and support the foremost print of the web prior, during and subsequent to separation from the next-following print or prints. The prints tend to curl or flex because they are separated from a web which is normally stored in convoluted condition, and such tendency to curl prevents accurate stacking of severed prints in the collecting receptacle. The absence of accurate stacking prevents or interferes with automatic processing of prints which accumulate in the receptacle, e.g., with automatic transport to an assembly station where all prints belonging to a customer are introduced into an envelope or box, together with the corresponding exposed and developed film or film sections, for shipment to the dealer or directly to the customer.
Another drawback of presently known severing and stacking apparatus is that they cannot discriminate between prints and other sections of webs of exposed and developed photographic paper, e.g., between the prints and the leaders or trailing ends of the webs. Each print is provided with a marker (e.g., an indicium at the rear side thereof) which is detected by a scanning device, and such detection serves to arrest the web in an optimum position for separation of the foremost print from the next-following print or prints. The leaders and trailing ends of webs are not formed with markers and they are often much longer than the prints. Indiscriminate mixing of such leaders and trailing ends with satisfactory prints further interferes with orderly removal of prints from the collecting receptacle and with predictable processing of removed commodities. The relatively long leaders and/or trailing ends must be removed by hand. Relatively long sections of web material need not necessarily be located at the front or rear end of a web; thus, it can happen that useless sections of photographic paper are located midway between the ends of a web if two or more webs are spliced together end-to-end to form a composite web of substantial length.